This invention is directed to the provision of natural turf surfaces in environments generally unsuited to the continued maintenance and growth of turf. One such environment is that present by a stadium, especially a stadium employed for multiple uses. As is widely appreciated, such stadia may be used both for football and baseball activities as well as for concerts, conventions and the like. This degree of usage presents such stress upon growing turf plants as to render the effective maintenance of natural turf surfaces under these conditions nearly impossible. The difficulties are exacerbated when a stadium is covered with a dome since the conditions obtaining within domed stadia are even more hostile to turf plants.
This invention is also directed to new, light weight growing media for the growth of plants, especially turf plants, and to methods for their employment.
While a number of workers have approached the design of improved stadium facilities for multiple uses and while a number of horticulturists have used varying means of transport for plant material within greenhouses, no effective means of providing well-groomed natural turf surfaces in stadia and playing fields has been known heretofore.
For example, U.S. Pat. No. 3,975,869 in the name of Bouton discloses a sports complex having movable seating units so as to configure the complex for varying activities such as football and baseball. U.S. Pat. No. 4,216,615--Soderberg et. al.--discloses a hothouse having moving beds for the cultivation of plants. U.S. Pat. No. 4,352,256 in the name of Kranz provides a greenhouse structure having a plurality of "spoke" units and a movable, central hub, plants growing within the spokes being transferrable into the hub region. U.S. Pat. No. 4,688,357--Deaton--is directed to configurable stadia with movable stands. The ability to provide differing contours over differently shaped surface areas is also provided including the moving of sections of playing field.
U.S. Pat. No. 4,837,971--Visser--is directed to greenhouses wherein plants can be moved from treatment to growing areas. U.S. Pat. No. 4,907,793 discloses an arrangement allowing varied use of a natural turf surface by covering the grass surface with supporting structure which is equipped with light source. While the covered surface is used, the underlying natural turf can continue photo-biological growth processes.
None of the foregoing provide natural turf surfaces for stadia, playing fields or the like suitable for the continued growth and maintenance of the turf in good condition.